Deformation and Fracture of L1₂ Trialuminides

Abstract

We review here recent experimental and theoretical work aimed at characterizing and understanding the deformation and fracture behavior of L1₂ trialuminides, with emphasis mainly on Al₃Ti-base alloys. We also review recent work on the binary compound Al₃Sc, which is a model L1₂ trialuminide that is being studied for comparison with first-principles quantum mechanical calculations. The topics covered in this review include: alloy-element effects and phase stability; dislocation structures; mechanical properties; cleavage fracture behavior; and first-principles calculations of elastic constants, fault energies, and ideal cleavage strengths. We discuss various possible reasons for the brittleness of these alloys, and summarize our current understanding of the rather unusual phenomenon of brittle cleavage in relatively soft materials having the high-symmetry L1₂ structure.